1. Field of the Invention
The present invention relates to a rotor component member, a rotating axis, and a rotor for a motor using a tapered sleeve, and a motor including the rotor, and a machine tool including the motor.
2. Description of the Related Art
In a rotor for a motor including a rotating axis and a sleeve mounted on an outer circumferential surface of the rotating axis, the sleeve is to be firmly fixed to the rotating axis such that a position of the sleeve relative to the rotating axis is not deviated during rotation of the rotor. In this regard, the rotor in which an inner circumferential surface of the sleeve is fitted on the outer circumferential surface of the rotating axis by interference fit so that the rotating axis and the sleeve are integrated with each other is known (for example, see Japanese Laid-open Patent Application No. 2013-9528 and Japanese Laid-open Patent Application No. H11-89142).
In Japanese Laid-open Patent Application No. 2013-9528, the outer circumferential surface of the rotating axis and the inner circumferential surface of the sleeve are each formed into a tapered shape. When the sleeve is mounted on the rotating axis, a lubricant is applied to the outer circumferential surface of the rotating axis, and the rotating axis is press-fitted along the inner circumferential surface of the sleeve. On the other hand, in Japanese Laid-open Patent Application No. H11-89142, an oil passage is formed in the sleeve, and high-pressure oil is introduced through the oil passage to a portion facing the inner circumferential surface of the sleeve. Due to hydraulic pressure caused by the high-pressure oil, an inner diameter of the sleeve is temporarily enlarged and the sleeve is fitted on the rotating axis.
However, in the rotor disclosed in Japanese Laid-open Patent Application No. 2013-9528 as described above, the lubricant is present on fitting surfaces of the rotating axis and the sleeve so that a friction force between the rotating axis and the sleeve reduces, and a position of the sleeve relative to the rotating axis may be deviated during high-speed rotation. Moreover, in the rotor disclosed in Japanese Laid-open Patent Application No. H11-89142 as described above, in order to supply hydraulic pressure to the inner circumferential surface of the sleeve, a hydraulic device is separately to be provided, and therefore manufacturing costs increase. Further, forming the oil passage in the sleeve causes the strength of the sleeve to be lowered.